1 files changed, 161 insertions, 0 deletions
diff --git a/guides/rails_guides/markdown.rb b/guides/rails_guides/markdown.rb
new file mode 100644
index 0000000000..650489e6cb
--- /dev/null
+++ b/guides/rails_guides/markdown.rb
@@ -0,0 +1,161 @@
+require 'redcarpet'
+require 'nokogiri'
+require 'rails_guides/markdown/renderer'
+
+module RailsGuides
+  class Markdown
+    def initialize(view, layout)
+      @view = view
+      @layout = layout
+      @index_counter = Hash.new(0)
+      @raw_header = ''
+      @node_ids = {}
+    end
+
+    def render(body)
+      @raw_body = body
+      extract_raw_header_and_body
+      generate_header
+      generate_title
+      generate_body
+      generate_structure
+      generate_index
+      render_page
+    end
+
+    private
+
+      def dom_id(nodes)
+        dom_id = dom_id_text(nodes.last.text)
+
+        # Fix duplicate node by prefix with its parent node
+        if @node_ids[dom_id]
+          if @node_ids[dom_id].size > 1
+            duplicate_nodes = @node_ids.delete(dom_id)
+            new_node_id = "#{duplicate_nodes[-2][:id]}-#{duplicate_nodes.last[:id]}"
+            duplicate_nodes.last[:id] = new_node_id
+            @node_ids[new_node_id] = duplicate_nodes
+          end
+
+          dom_id = "#{nodes[-2][:id]}-#{dom_id}"
+        end
+
+        @node_ids[dom_id] = nodes
+        dom_id
+      end
+
+      def dom_id_text(text)
+        text.downcase.gsub(/\?/, '-questionmark').gsub(/!/, '-bang').gsub(/[^a-z0-9]+/, ' ')
+          .strip.gsub(/\s+/, '-')
+      end
+
+      def engine
+        @engine ||= Redcarpet::Markdown.new(Renderer, {
+          no_intra_emphasis: true,
+          fenced_code_blocks: true,
+          autolink: true,
+          strikethrough: true,
+          superscript: true,
+          tables: true
+        })
+      end
+
+      def extract_raw_header_and_body
+        if @raw_body =~ /^\-{40,}$/
+          @raw_header, _, @raw_body = @raw_body.partition(/^\-{40,}$/).map(&:strip)
+        end
+      end
+
+      def generate_body
+        @body = engine.render(@raw_body)
+      end
+
+      def generate_header
+        @header = engine.render(@raw_header).html_safe
+      end
+
+      def generate_structure
+        @headings_for_index = []
+        if @body.present?
+          @body = Nokogiri::HTML(@body).tap do |doc|
+            hierarchy = []
+
+            doc.at('body').children.each do |node|
+              if node.name =~ /^h[3-6]$/
+                case node.name
+                when 'h3'
+                  hierarchy = [node]
+                  @headings_for_index << [1, node, node.inner_html]
+                when 'h4'
+                  hierarchy = hierarchy[0, 1] + [node]
+                  @headings_for_index << [2, node, node.inner_html]
+                when 'h5'
+                  hierarchy = hierarchy[0, 2] + [node]
+                when 'h6'
+                  hierarchy = hierarchy[0, 3] + [node]
+                end
+
+                node[:id] = dom_id(hierarchy)
+                node.inner_html = "#{node_index(hierarchy)} #{node.inner_html}"
+              end
+            end
+          end.to_html
+        end
+      end
+
+      def generate_index
+        if @headings_for_index.present?
+          raw_index = ''
+          @headings_for_index.each do |level, node, label|
+            if level == 1
+              raw_index += "1. [#{label}](##{node[:id]})\n"
+            elsif level == 2
+              raw_index += "    * [#{label}](##{node[:id]})\n"
+            end
+          end
+
+          @index = Nokogiri::HTML(engine.render(raw_index)).tap do |doc|
+            doc.at('ol')[:class] = 'chapters'
+          end.to_html
+
+          @index = <<-INDEX.html_safe
+          <div id="subCol">
+            <h3 class="chapter"><img src="images/chapters_icon.gif" alt="" />Chapters</h3>
+            #{@index}
+          </div>
+          INDEX
+        end
+      end
+
+      def generate_title
+        if heading = Nokogiri::HTML(@header).at(:h2)
+          @title = "Ruby on Rails Guides: #{heading.text}".html_safe
+        else
+          @title = "Ruby on Rails Guides"
+        end
+      end
+
+      def node_index(hierarchy)
+        case hierarchy.size
+        when 1
+          @index_counter[2] = @index_counter[3] = @index_counter[4] = 0
+          "#{@index_counter[1] += 1}"
+        when 2
+          @index_counter[3] = @index_counter[4] = 0
+          "#{@index_counter[1]}.#{@index_counter[2] += 1}"
+        when 3
+          @index_counter[4] = 0
+          "#{@index_counter[1]}.#{@index_counter[2]}.#{@index_counter[3] += 1}"
+        when 4
+          "#{@index_counter[1]}.#{@index_counter[2]}.#{@index_counter[3]}.#{@index_counter[4] += 1}"
+        end
+      end
+
+      def render_page
+        @view.content_for(:header_section) { @header }
+        @view.content_for(:page_title) { @title }
+        @view.content_for(:index_section) { @index }
+        @view.render(:layout => @layout, :text => @body)
+      end
+  end
+end